Journal
MICROPOROUS AND MESOPOROUS MATERIALS
Volume 142, Issue 1, Pages 70-81Publisher
ELSEVIER
DOI: 10.1016/j.micromeso.2010.11.019
Keywords
Hierarchical meso-macroporosity; Aluminosilicate; High tetrahedral Al content; Single molecular precursor; Tetraalkoxysilane co-reactants
Categories
Funding
- European Community
- Wallonia region
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The effect of tetraethoxysilane (TEOS), tetrapropoxysilane (TPOS), tetrabutoxysilane (TBOS) and a mixture of tetramethoxysilane (TMOS) and TEOS as silicon co-reactant on the formation of hierarchically structured meso-macroporous aluminosilicates and the tetrahedral aluminium content in the framework using a single molecular alkoxide precursor, (sec-BuO)2-Al-O-Si(OEt)(3), has been intensively investigated. The use of alkoxysilane as a co-reactant and highly alkaline media improves the heterocondensation rates between the highly reactive aluminium-alkoxide part of the single molecular precursor and the added alkoxysilanes, and minimizes the cleavage of the intrinsic Al-O-Si linkage. The very unique hierarchical meso-macroporosity was auto-generated by the hydrodynamic flow of solvents released during the rapid hydrolysis and condensation processes of this double alkoxide and the inorganic silica co-reactant. No external structural agent was required to template these porous structures. The particles obtained featured outstanding macrostructure with regular micrometer-sized macrovoids and displaying 3D interconnections. Importantly, the diameter of the micrometer-sized macrovoids found in the final materials and the thickness of the mesoporous walls separating these voids can be tuned by adjusting the reactivity of alkoxysilanes used as co-reactant. Higher reactivity of alkoxysilanes can improve the tetrahedral aluminium content in the meso-macroporous framework and reduce the cleavage of Al-O-Si linkage of the single molecular precursor. These correlations are of primary importance for targeting advanced materials with well defined meso- and macroporosities and tetrahedral aluminium content. (C) 2010 Elsevier Inc. All rights reserved.
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